Solar Water Heater

The Salvage Solar Water Heater Project

Administered by Watershed Management Group  of  Tucson  Arizona

Facilitated by Barton


WMG has asked me to facilitate the development of a solar water heater co-op work shop program.  During the development process I will be doing 3 work shops, and one proto type.  I will post dates and locations as I get them.

This is one I did near Dos Cabezas with an old fridge from next door, a 30 gallon tank I found on the side of the road and a $10.00 shower door from habitat. It had ranch hose for plumbing and It worked fine. It was real ugly. I cleaned it up and painted it green before I left. It needed a clear door.





This is the general concept of the system I’m going to use for the first workshops

Solar Water Heater Concept

So what you need is:

A tank 30-40 gallons designed to be used for a water heater, with pressure relief valve, painted black with rust proofing or fire-proof paint. Tanks can easily be found salvage, new they are about $250.00, either way you have to remove the stuff around the tank and paint it black. You end up with either some large pieces of trash or useful salvage, depending on your view point.

A box to fit the tank and the glass, almost any wood or metal box of the dimensions to fit the tank plus 2″ or more clearance all around the sides of the tank.There should be as little over hang of glass as possible. It’s better to have to frame in for the glass than to have the glass over hanging the edge. I’m considering doing one in a fridge with the sliding glass door then cobbing, or light clay straw pile, the outside of the fridge to fit the glass and add thermal mass. as well as blending in with close by cob wall and outdoor shower.

Some people say make the interior shiny like with foil others say paint it black. I like layering it with some kind of foil even if it’s just the backing on celotex and other foams. Foil would give a nice finished look to any surface. Black I think is more for ovens we want the heat focused on the tank. The foil can be shaped as a parabolic or curved surface focusing the sun on the tank, this should be somewhat more efficient if you can get your foil to lay down smooth in the arc.

This box might need to be lined with insulation 2″- 4″ of heat resistant foam or equivalent R-value. R-Max Thermo Shield 3 sold at box stores is the right type of foam. Using 2 or more layers of the thinner panels like Celotex with 1/4″ to 1/2″ gaps gives you an increase in R value that is significant. Some people say it’s ok to use styrene, some say it isn’t. It would be interesting to test different types of recycled insulation to see what kind of “trash” we could use. I think casting papercrete or forming loose clay cob cabinets might work well possibly in conjunction with other insulating materials (Styrofoam egg cartons, coffee cups).

I helped make a trash paper and adobe mix wall that formed well and might lend itself to this application Check out the flickr set Good way to use trash and makes a good wall. Has to be covered with a capstone and linseed oil or other coating.

The proto-type is likely to be a sloping, vertically oriented, cob cabinet with 3′ x 6′ sliding glass door for the front an an insulated door for access in the rear.  I may line the inner walls with celotex with the shiny side in.

Double glazed tempered glass to fit the opening,  sliding glass doors, shower doors, table tops, any tempered glass. New, you are looking at $150.00 to $300.00 depending on single or double pane.  Sliding glass doors are $20.00-$40.00 at salvage yards. Shower doors work better for fridges. They are usually bordered in channel aluminum and you can run a wire through them or drive in a screw to allow you to fasten the frame to the box. The one I had fit the fridge perfectly. These are $10.00-20.00 at salvage yards. A shower door and fridge has a little less collection area as is so may not be quite as efficient as the 4’x6′ design. You could build an insulated door that was also a reflector and increase the collection area and keep the water hot overnight.

Copper tubing and fittings with shut off valves to connect to the tank through the cabinet wall. These should be sized to fit your tank fittings and the plumbing you are tying in to.

Barnett and Shore a local salvage yard here in Tucson has pretty much everything you would need for under $100.00








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